Racial disparities in cancer treatment contribute significantly to Black-White differences in mortality and survival. Our prior collaborations with our community, our research, and the research of others suggest that Black-White disparities in the quality of communication and information exchange during clinical interactions often lead Black patients to refuse appropriate treatments and oncologists to plan treatments for their Black patients that are inconsistent with clinical practice guidelines. We propose a community-based participatory research (CBPR) approach to developing and testing an intervention to change Black patients' attitudes toward and behavior during clinical interactions, thus changing their own and their oncologists' beliefs and attitudes related to treatment. This, in turn, will result in more appropriate patient and oncologist treatment decisions for older African American cancer patients. Our highly experienced multidisciplinary team of researchers and active community stakeholders have extensive experience collaborating to conduct research to reduce Black-White health disparities in southeast Michigan. For this intervention study, we will recruit medical oncologists from two cancer centers and their African American patients before an appointment to discuss curative chemotherapy for breast, colorectal, or lung cancer. Our intervention is designed to encourage patients to participate actively in the clinical interaction with their oncologist The intervention has two components: a question prompt list (QPL), which suggests questions that patients might want to consider asking their oncologist; and a patient advocate, matched to the patient's gender and race and specially trained to encourage patients to participate actively in the interaction. We will randomize patients into one of three arms. Patients in the first arm will receive standard of care. Patients in the second arm will receive only the QPL priorto the interaction. Patients in the third arm will receive both the QPL and the assistance of a patient advocate. We will administer self-report questionnaires and video record the clinical interaction so that we can assess patients and oncologists before, during, and after the interaction. The primary goal of our intervention is to improve the likelihood that patients and oncologists will make an appropriate treatment decision. Secondary outcomes will be improvements in the quality of communication and information exchange during the interactions and attitudes and beliefs related to the decisions. The proposed research is both innovative and significant. First, we base our research on an innovative, theoretically-driven model explaining how communication and information exchange during clinical interactions can affect patient and physician treatment-related attitudes and beliefs, and thus treatment disparities. In collaboration with our community partners, the model leads to a practical intervention combining the improvement of patient communication skills and attitudes with the assistance of a patient advocate, which will encourage patients to participate actively in oncology interactions. The study is significant because it will result in a feasible, effective, and exportable intervention to reduce well-documented treatment disparities.